My Big Campus is an educational social media system that is run through the county's Lightspeed Security System. It is the base of my overall instruction in the classroom. I find that many students are able to complete their work from home because of an illness or on a vacation because of this site. The site has an option to email you when someone responds to a topic. The system is run very similar to edmodo as described below. Click here for a video tutorial.
www.edmodo.com is a website that utilizes collaboration both for teachers and students. It is very similar to Facebook in how you communicate with one another. The students cannot do anything other than join the groups in which the teacher creates. These groups have special codes. The students can then post and respond to anyone in that group. Click here for a video tutorial. See examples below: